ThreeWindingTransformer
Package: PowerOperationsOpenAPIModels · Source: Operations/Branch/ThreeWindingTransformer.json
A three-winding transformer, modeled as an equivalent star: each referenced TransformerCircuit connects a terminal bus to the star (hidden) bus and carries that winding’s series electrical data; availability is circuit-level. The pairwise measured impedances r_12/x_12, r_23/x_23, r_31/x_31 (PSS/E CZ = 1, each in pu on the corresponding base_power_12/base_power_23/base_power_31 and referenced to the first-index winding’s base voltage) are optional and must be set together or all be absent; the star-leg impedances derived from them at parse time live on the circuits and are not synced back. Power-flow and Ybus assembly read the per-circuit star-leg impedances, not the pairwise fields. The model is described in Chapter 3.6 of J.D. Glover, M.S. Sarma and T. Overbye: Power Systems Analysis and Design.
Properties
| Property | Type | Required | Unit | Description |
|---|---|---|---|---|
id | integer | yes | — | Unique integer identifier for this component. |
name | string | yes | — | Name of the component. Components of the same type (e.g., PowerLoad) must have unique names, but components of different types (e.g., PowerLoad and ACBus) can have the same name. |
primary_circuit | integer | yes | — | The primary TransformerCircuit connecting the primary bus to the star bus. |
secondary_circuit | integer | yes | — | The secondary TransformerCircuit connecting the secondary bus to the star bus. |
tertiary_circuit | integer | yes | — | The tertiary TransformerCircuit connecting the tertiary bus to the star bus. |
star_bus | integer | yes | — | Star (hidden) Bus that this component (equivalent model) is connected to. |
parameter_units | string (ImpedanceUnitBasis) | — | — | Unit basis for the pairwise measured impedance fields (r_12, x_12, r_23, x_23, r_31, x_31). PSS/E supplies a single CZ flag for the whole three-winding transformer record, so one basis governs all three winding pairs. |
r_12 | number | — | ohm / pu (by parameter_units) | Measured resistance, referenced to the primary winding’s base voltage, from primary to secondary windings (R1-2 in PSS/E). Units: per parameter_units — NATURAL_UNITS: ohm, COMPONENT_BASE: pu . |
x_12 | number | — | ohm / pu (by parameter_units) | Measured reactance, referenced to the primary winding’s base voltage, from primary to secondary windings (X1-2 in PSS/E). Units: per parameter_units — NATURAL_UNITS: ohm, COMPONENT_BASE: pu . |
r_23 | number | — | ohm / pu (by parameter_units) | Measured resistance, referenced to the secondary winding’s base voltage, from secondary to tertiary windings (R2-3 in PSS/E). Units: per parameter_units — NATURAL_UNITS: ohm, COMPONENT_BASE: pu . |
x_23 | number | — | ohm / pu (by parameter_units) | Measured reactance, referenced to the secondary winding’s base voltage, from secondary to tertiary windings (X2-3 in PSS/E). Units: per parameter_units — NATURAL_UNITS: ohm, COMPONENT_BASE: pu . |
r_31 | number | — | ohm / pu (by parameter_units) | Measured resistance, referenced to the tertiary winding’s base voltage, from tertiary to primary windings (R3-1 in PSS/E). Units: per parameter_units — NATURAL_UNITS: ohm, COMPONENT_BASE: pu . |
x_31 | number | — | ohm / pu (by parameter_units) | Measured reactance, referenced to the tertiary winding’s base voltage, from tertiary to primary windings (X3-1 in PSS/E). Units: per parameter_units — NATURAL_UNITS: ohm, COMPONENT_BASE: pu . |
base_power_12 | number | — | MVA | Base power for per unitization for primary-secondary windings. Units: MVA. |
base_power_23 | number | — | MVA | Base power for per unitization for secondary-tertiary windings. Units: MVA. |
base_power_31 | number | — | MVA | Base power for per unitization for tertiary-primary windings. Units: MVA. |
admittance_units | string (AdmittanceUnitBasis) | — | — | Unit basis for the magnetizing_shunt admittance. |
magnetizing_shunt | ComplexNumber | — | S / MVAr / pu (by admittance_units) | Magnetizing shunt admittance referenced to the primary circuit’s base voltage. Units: per admittance_units — NATURAL_UNITS: S, COMPONENT_MVAR: MVAr, COMPONENT_BASE: pu . |
shunt_location | string (ThreeWindingTransformerShuntLocation) | — | — | Placement of magnetizing_shunt in the equivalent star model. |